Robotic surgical assemblies

ABSTRACT

An instrument drive unit includes a hub, a motor pack, and an annular member disposed between the hub and the motor pack. The hub and motor pack each have a surface feature. The motor pack is rotatably coupled to the hub. The annular member defines an upper annular channel, and a lower annular channel. The annular member has a stop formed in each of the upper and lower annular channels. Upon the motor pack achieving a threshold amount of rotation relative to the hub, the surface feature of the motor pack abuts the stop of the lower annular channel to rotate the annular member. Upon the annular member achieving a threshold amount of rotation relative to the hub, the stop of the upper annular channel abuts the surface feature of the hub stopping further rotation of the motor pack.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation Application of U.S. patentapplication Ser. No. 16/081,335, filed on Aug. 30, 2018, which is aNational Stage Entry of International Patent Application No.PCT/US2017/19584, filed on Feb. 27, 2017, which claims the benefit ofand priority to U.S. Provisional Patent Application Ser. No. 62/303,574,filed on Mar. 4, 2016, the entire contents of each of which areincorporated herein by reference.

BACKGROUND

Robotic surgical systems have been used in minimally invasive medicalprocedures. Some robotic surgical systems included a console supportinga surgical robotic arm and a surgical instrument, having at least oneend effector (e.g., forceps or a grasping tool), mounted to the roboticarm. The robotic arm provided mechanical power to the surgicalinstrument for its operation and movement.

Manually-operated surgical instruments often included a handle assemblyfor actuating the functions of the surgical instrument. However, whenusing a robotic surgical system, no handle assembly was typicallypresent to actuate the functions of the end effector. Accordingly, touse each unique surgical instrument with a robotic surgical system, aninstrument drive unit was used to interface with the selected surgicalinstrument to drive operations of the surgical instrument.

Typically, an inner component of the instrument drive unit was rotatedto rotate the surgical instrument about its longitudinal axis. Makingthe instrument drive unit rotatable provides for a more simplifiedsurgical instrument including staplers, electrosurgical instruments, andstraight instruments. However, there is a limit to the amount theinstrument drive unit and surgical instrument can rotate without causingdamage to their internal components.

Accordingly, a need exists for a way of either monitoring and/orcontrolling the amount the instrument drive unit and/or surgicalinstrument is rotated.

SUMMARY

In accordance with an aspect of the present disclosure, an instrumentdrive unit for use with a robotic arm is provided. The instrument driveunit includes an outer shell and an inner shell removably receivedwithin the outer shell. The outer shell is configured to be selectivelycoupled to a robotic arm. The inner shell includes a hub, a motor pack,and an annular member. The hub is non-rotatably received within theouter shell and has a distally extending surface feature. The motor packincludes a proximal end rotatably coupled to the hub and a surfacefeature extending proximally from the proximal end thereof. The annularmember defines an upper annular channel and a lower annular channel. Theupper annular channel has the surface feature of the hub receivedtherein. The lower annular channel has the surface feature of the motorpack received therein. The annular member has a stop formed in each ofthe upper and lower annular channels. Upon the motor pack achieving athreshold amount of rotation relative to the hub, the surface feature ofthe motor pack abuts the stop of the lower annular channel to rotate theannular member relative to the hub. Upon the annular member achieving athreshold amount of rotation relative to the hub, the stop of the upperannular channel abuts the surface feature of the hub stopping furtherrotation of the motor pack.

In some embodiments, each of the proximal end of the motor pack, theannular member, and the hub may have a sensor in communication with oneanother and configured to sense the relative rotational positions of oneanother. The sensor of the motor pack may be disposed adjacent thesurface feature thereof. The sensor of the annular member may bedisposed adjacent the stop of the upper or lower annular channels. Thesensor of the hub may be disposed adjacent the surface feature thereof.The sensors of each of the motor pack, the annular member, and the hubmay be hall effect sensors, rotary variable differential transformers,variable reluctance sensors, potentiometers, capacitive rotary positionsensors, optical encoders, or laser surface velocimeters.

It is contemplated that the threshold amount of rotation of the motorpack relative to the hub may be approximately 1 to 360 degrees,threshold amount of rotation of the annular member relative to the hubmay be approximately 1 to 360 degrees, such that the motor pack isconfigured to rotate approximately 2 to 720 degrees relative to theouter shell.

It is envisioned that the annular member may be a hollow ring having anH-shaped transverse cross sectional profile.

In some aspects of the present disclosure, the surface feature of themotor pack may be a curved projection slidably received within the lowerannular channel of the annular member. The surface feature of the hubmay be a curved projection slidably received within the upper annularchannel of the annular member.

In another aspect of the present disclosure, a surgical assembly for usewith and for selective connection to a robotic arm is provided. Thesurgical assembly includes an instrument drive unit. The instrumentdrive unit includes a hub, a motor pack, and an annular member. The hubhas a surface feature. The motor pack has a surface feature and isrotatably coupled to the hub. The annular member is disposed between thehub and the motor pack. The annular member defines an upper annularchannel and a lower annular channel. The annular member has a stopformed in each of the upper and lower annular channels. Upon the motorpack achieving a threshold amount of rotation relative to the hub, thesurface feature of the motor pack abuts the stop of the lower annularchannel to rotate the annular member. Upon the annular member achievinga threshold amount of rotation relative to the hub, the stop of theupper annular channel abuts the surface feature of the hub stoppingfurther rotation of the motor pack.

In some embodiments, the instrument drive unit may further include anouter shell. The hub may be non-rotatably received within the outershell. The surgical assembly may further include a surgical instrumentholder that includes a carriage housing and a motor disposed within thecarriage housing. The carriage housing may have a first side configuredfor movable engagement to a surgical robotic arm, and a second sideconfigured for non-rotatably supporting the outer shell of theinstrument drive unit. The motor may be configured to effect rotation ofthe motor pack of the instrument drive unit.

It is envisioned that the surgical instrument holder may further includecontrol circuitry disposed within the carriage housing and incommunication with the motor and a sensor of each of the motor pack, theannular member, and the hub. The control circuitry is configured to stopoperation of the motor upon the stop of the upper annular channel beingdisposed adjacent the surface feature of the hub.

It is contemplated that the surface feature of the hub may extenddistally from the hub, and the surface feature of the motor pack mayextend proximally from the proximal end thereof. The motor pack may havea proximal end rotatably coupled to the hub.

In some aspects of the present disclosure, the motor pack may have adistal end configured to be non-rotatably coupled to a proximal end ofan electromechanical instrument. The motor pack of the instrument driveunit may be configured to actuate functions of the electromechanicalinstrument. The electromechanical instrument may rotate with rotation ofthe motor pack of the instrument drive unit.

In yet another aspect of the present disclosure, an instrument driveunit for use with a robotic arm is provided and includes an outer shellconfigured to be coupled to a robotic arm, a drive motor, an interface,and a drive motor output. The drive motor is selectively moveable in anorbit within the outer shell around a central axis. The interface iscoupled to the outer shell and configured to be selectively couplable toa surgical instrument. The drive motor output is coupled to the drivemotor and configured to be coupled to an input of a surgical instrumentwhen the interface is coupled to an interface of a surgical instrument.

In some embodiments, the drive motor may be encased within the outershell.

It is contemplated that the outer shell may remain stationary when thedrive motor is selectively moved in the orbit. The drive motor may be aplurality of drive motors selectively movable as a group in the orbitwithin the outer shell. Each of the drive motors may have a drive motoroutput configured to be coupled to a respective input of a surgicalinstrument. The instrument drive unit may be configured to rotate thesurgical instrument about the central axis when the interface of theinstrument drive unit is selectively coupled to an interface of thesurgical instrument.

It is envisioned that the instrument drive unit may further include anelectro-mechanical actuator coupled to at least one of the drive motors.The electro-mechanical actuator is configured to rotate the surgicalinstrument about the central axis while moving the drive motors, thedrive motor outputs, and the respective inputs of the surgicalinstrument in the orbit within the outer shell when the interface of thesurgical instrument is selectively coupled to the interface of theinstrument drive unit.

In yet another aspect of the present disclosure, another embodiment ofan instrument drive unit for use with a robotic arm is provided. Theinstrument drive unit includes an outer shell configured to beselectively coupled to a robotic arm, and an inner shell removablyreceived within the outer shell. The inner shell includes a hub, a motorpack, and first and second annular members. The hub is non-rotatablyreceived within the outer shell and has a distally extending surfacefeature. The motor pack includes a proximal end rotatably coupled to thehub, and a surface feature extending proximally from the proximal endthereof. The first annular member defines an upper annular channelhaving the surface feature of the hub received therein. The firstannular member has a stop formed in the upper channel thereof. Thesecond annular member is associated with the first annular member anddefines a lower annular channel. The second annular member has a stopformed in the lower annular channel thereof. Upon the motor packachieving a threshold amount of rotation relative to the hub, thesurface feature of the motor pack abuts the stop of the lower annularchannel of the second annular member to rotate the second annular memberrelative to the hub. Upon the first annular member achieving a thresholdamount of rotation relative to the hub, the stop of the upper annularchannel of the first annular member abuts the surface feature of the hubstopping further rotation of the motor pack.

In some embodiments, the instrument drive unit may include a thirdannular member interposed between the first and second annular members.

Further details and aspects of exemplary embodiments of the presentdisclosure are described in more detail below with reference to theappended figures.

As used herein, the terms parallel and perpendicular are understood toinclude relative configurations that are substantially parallel andsubstantially perpendicular up to about + or −10 degrees from trueparallel and true perpendicular.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described herein withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a robotic surgical systemincluding a surgical assembly in accordance with the present disclosure;

FIG. 2A is a front, perspective view of the surgical assembly of FIG. 1including a slider, a surgical instrument holder, an instrument driveunit, and a surgical instrument;

FIG. 2B is a rear, perspective view of the surgical assembly of FIG. 1including the slider, the surgical instrument holder, the instrumentdrive unit, and the surgical instrument;

FIG. 3 is a perspective view of the instrument drive unit of FIG. 1including an outer shell and an inner shell;

FIG. 4 is a longitudinal cross-sectional view of the instrument driveunit of FIG. 3 including a rotational position sensing system, accordingto an embodiment of the present disclosure;

FIG. 5 is a top, perspective view, with parts separated, of therotational position sensing system of FIG. 4 ;

FIG. 6 . is a bottom view of an annular member of the rotationalposition sensing system of FIG. 5 ;

FIG. 7 is a perspective view of a series of annular members of anotherembodiment of a rotational position sensing system used with theinstrument drive unit of FIG. 1 ; and

FIG. 8 is a bottom view of one of the series of annular members of FIG.7 .

DETAILED DESCRIPTION

Embodiments of the presently disclosed surgical assembly including aninstrument drive unit for driving the operation of an electromechanicalinstrument, a rotational position sensing system, and methods thereofare described in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As used herein the term “distal” refers to thatportion of the robotic surgical system, surgical assembly, or componentthereof, that is closest to the patient, while the term “proximal”refers to that portion of the robotic surgical system, surgicalassembly, or component thereof, further from the patient.

As will be described in detail below, provided is a surgical assemblyconfigured to be attached to a surgical robotic arm. The surgicalassembly includes an instrument drive unit configured to rotate asurgical instrument about a longitudinal axis thereof. The instrumentdrive unit includes a rotational position sensing system configured todetermine and regulate the degree of rotation of the surgical instrumentabout its longitudinal axis.

Referring initially to FIGS. 1 and 2 , a surgical system, such as, forexample, a robotic surgical system 1, generally includes a plurality ofsurgical robotic arms 2, 3 having an instrument drive unit 100 and anelectromechanical instrument 10 removably attached thereto; a controldevice 4; and an operating console 5 coupled with control device 4.

Operating console 5 includes a display device 6, which is set up inparticular to display three-dimensional images; and manual input devices7, 8, by means of which a person (not shown), for example a surgeon, isable to telemanipulate robotic arms 2, 3 in a first operating mode, asknown in principle to a person skilled in the art. Each of the roboticarms 2, 3 may be composed of a plurality of members, which are connectedthrough joints. Robotic arms 2, 3 may be driven by electric drives (notshown) that are connected to control device 4. Control device 4 (e.g., acomputer) is set up to activate the drives, in particular by means of acomputer program, in such a way that robotic arms 2, 3, the attachedinstrument drive units 100, and thus electromechanical instrument 10execute a desired movement according to a movement defined by means ofmanual input devices 7, 8. Control device 4 may also be set up in such away that it regulates the movement of robotic arms 2, 3 and/or of thedrives.

Robotic surgical system 1 is configured for use on a patient “P” lyingon a surgical table “ST” to be treated in a minimally invasive manner bymeans of a surgical instrument, e.g., electromechanical instrument 10.Robotic surgical system 1 may also include more than two robotic arms 2,3, the additional robotic arms likewise being connected to controldevice 4 and being telemanipulatable by means of operating console 5. Asurgical instrument, for example, electromechanical surgical instrument10 (including an electromechanical end effector (not shown)), may alsobe attached to the additional robotic arm.

Control device 4 may control a plurality of motors, e.g., motors (Motor1 . . . n), with each motor configured to drive movement of robotic arms2, 3 in a plurality of directions. Further, control device 4 may controla motor pack 122 (FIG. 3 ) of instrument drive unit 100 to drive variousoperations of surgical instrument 10, and may control a rotation ofmotor pack 122 of instrument drive unit 100 to ultimately rotateelectromechanical instrument 10 along a longitudinal axis “X” thereof,as will be described in detail below. Motor pack 122 includes aplurality of drive motors 125 a, 125 b having respective drive motoroutputs 127 a, 127 b configured to be coupled to respective inputs ofthe surgical instrument 10. In embodiments, each drive motor 125 a, 125b of motor pack 122 can be configured to actuate a drive rod or a leverarm to effect operation and/or movement of each electromechanical endeffector (not shown) of electromechanical instrument 10. In someembodiments, motor pack 122 of instrument drive unit 100 can be used todrive a lead screw (not explicitly shown) of the electromechanicalsurgical instrument 10.

For a detailed description of the construction and operation of arobotic surgical system, reference may be made to U.S. Pat. No.8,828,023, the entire contents of which are incorporated by referenceherein.

With continued reference to FIGS. 1 and 2 , robotic surgical system 1includes a surgical assembly 30, which includes a surgical instrumentholder 102 coupled with or to robotic arm 2, the instrument drive unit100 coupled to surgical instrument holder 102, and the electromechanicalinstrument 10 coupled to instrument drive unit 100. Surgical instrumentholder 102 of surgical assembly 30 holds instrument drive unit 100 andsurgical instrument 10 and operably couples instrument drive unit 100 torobotic arm 2. Surgical instrument holder 102 includes an interfacepanel or carriage 104 and an outer housing portion 108 extendingperpendicularly from an end of carriage 104. Carriage 104 supports orhouses a motor “M,” which receives controls and power from controldevice 4. Carriage 104 has a first side 104 a, and a second side 104 b.First side 104 a of carriage 104 is slidably mounted onto a rail 40 ofrobotic arm 2. Carriage 104 may be moved along rail 40 via a motordriven chain or belt (not shown) or the like. Second side 104 b ofcarriage 104 of surgical instrument holder 102 is configured fornon-rotatable attachment of an outer shell 110 of instrument drive unit100.

Outer housing portion 108 of surgical instrument holder 102 defines apassageway (not shown) therethrough configured to receive a distal endor interface 122 b of a motor pack 122 of instrument drive unit 100. Assuch, when instrument drive unit 100 is attached to surgical instrumentholder 102, outer shell 110 of instrument drive unit 100 isnon-rotatably connected to second side 104 b of carriage 104, and distalend or interface 122 b of motor pack 122 of instrument drive unit 100 isrotatably received within the passageway of outer housing portion 108 ofsurgical instrument holder 102.

Surgical instrument holder 102 further includes control circuitry 109disposed within carriage 104. Control circuitry 109 is in communicationwith an electro-mechanical actuator, such as, for example, a motor “M”to control the operation of motor “M.” Motor “M” is configured to beoperably coupled to motor pack 122 of instrument drive unit 100 to drivea rotation of motor pack 122. In some embodiments, control circuitry 109may be disposed within any of the components of surgical assembly 30.

With reference to FIGS. 3 and 4 , instrument drive unit 100 transferspower and actuation forces from its motors (FIG. 4 ) to driven members(not shown) of electromechanical instrument 10 (FIG. 2 ) to ultimatelydrive movement of components of the end effector (not shown) ofelectromechanical instrument 10, for example, a movement of a knifeblade (not shown) and/or a closing and opening of jaw members (notshown) of the end effector. Instrument drive unit 100 generally includesan outer shell 110 and an inner shell 120 disposed within outer shell110.

Outer shell 110 of instrument drive unit 100 encloses the innercomponents of instrument drive unit 100 to form a sterile barrierbetween an interior of instrument drive unit 100 and the externalenvironment. Outer shell 110 may be disposable, re-usable (uponsterilization), and/or transparent. Outer shell 110 defines a cavity(not shown) therein for removable receipt of inner shell 120 ofinstrument drive unit 100. Outer shell has a generally U-shaped portion110 a and a cylindrical body 110 b extending distally from U-shapedportion 110 a. U-shaped portion 110 a of outer shell 110 has a lid 112that is selectively opened during removal or insertion of inner shell120 within outer shell 110.

Inner shell 120 of instrument drive unit 100 is removably receivablewithin outer shell 110 of instrument drive unit 100. Inner shell 120 ofinstrument drive unit 100 includes a hub 124 and a motor pack 122rotatably coupled to hub 124 and extending distally therefrom. Hub 124of inner shell 120 has a shape corresponding to U-shaped portion 110 aof outer shell 110 such that hub 124 is non-rotatably received withinU-shaped portion 110 a of outer shell 110. Hub 124 of inner shell 120has a surface feature 126 extending distally from a distal end thereof.Surface feature 126 is fixed to hub 124 and is slidably received withinan upper channel 140 a of an annular member 140, as will be described indetail below. Surface feature 126 is a curved projection, but it iscontemplated that surface feature 126 may be a tab or a block assuming avariety of shapes, such as, for example, triangular, arcuate, polygonal,uniform, non-uniform, tapered, or the like.

Hub 124 of inner shell 120 of instrument drive unit 100 further includesa sensor s126 (FIG. 5 ) disposed adjacent to or on surface feature 126thereof. Sensor s126 of hub 124 is in communication with controlcircuitry 109 (FIG. 2 ) of surgical instrument holder 102 to communicateits location to control circuitry 109, as will be described in detailbelow.

With continued reference to FIGS. 3 and 4 , motor pack 122 of innershell 120 of instrument drive unit 100 has a shape corresponding tocylindrical body 110 b of outer shell 110 of instrument drive unit 100such that motor pack 122 is rotatably receivable within cylindrical body110 b of outer shell 110 of instrument drive unit 100. Motor pack 122 ofinner shell 120 has a proximal end 122 a that is rotatably coupled tohub 124 of inner shell 110. Motor pack 122 has a surface feature 128(FIG. 5 ) extending proximally from proximal end 122 a thereof. Surfacefeature 128 of motor pack 122 is fixed to the proximal end 122 a thereofand is slidably received within a lower channel 140 b of annular member140. Surface feature 128 of motor pack 122 is a curved projection, butit is contemplated that surface feature 128 may be a tab or a blockassuming a variety of shapes, such as, for example, triangular, arcuate,polygonal, uniform, non-uniform, tapered, or the like.

Motor pack 122 further includes a sensor s122 (FIG. 5 ) disposedadjacent to or on surface feature 128 thereof. Sensor s122 of motor pack122 is in communication with control circuitry 109 (FIG. 2 ) of surgicalinstrument holder 102 and sensor s126 of hub 124 to communicate itslocation (e.g., angular location) relative to sensor s126 of hub 124 tocontrol circuitry 109.

Motor pack 122 is operably coupled to motor “M” (FIG. 2 ) of surgicalinstrument holder 102 by any suitable drive mechanism, for example, apulley system. As such, motor pack 122 of inner shell 120 is rotatedwithin outer shell 110 and relative to hub 124 of inner shell 120 viaactuation of motor “M” of surgical instrument holder 102. Motor pack 122may include four motors arranged in a rectangular formation such thatrespective drive shafts (not shown) thereof are all parallel to oneanother and all extending in a common direction. The drive shaft of eachmotor may operatively interface with a respective driven shaft ofsurgical instrument 10 to independently actuate the driven shafts ofsurgical instrument 10.

With reference to FIGS. 4-6 , instrument drive unit 100 includes arotational position sensor system 130 configured to determine andindicate the degree to which motor pack 122, and therefore, surgicalinstrument 10, rotates about longitudinal axis “X.” It is contemplatedthat sensor system 130 may be configured to calculate/determine anddisplay the amount of revolution(s) of surgical instrument 10 relativeto outer shell 110 (FIG. 3 ) of instrument drive unit 100 aboutlongitudinal axis “X,” so that a clinician can determine the preciserotational position of surgical instrument 10 during use thereof.

Sensor system 130 includes the control circuitry 109 (FIG. 2 ) ofsurgical instrument holder 102, sensors s126, s122 of hub 124 and motorpack 122, respectively, and an annular member 140. Annular member 140 isrotatably disposed between hub 124 of instrument drive unit 100 andmotor pack 122 of instrument drive unit 100. Annular member 140 is ahollow ring, and defines an upper annular channel 140 a and a lowerannular channel 140 b. As such, annular member 140 has an H-shapedtransverse cross-sectional profile. Upper annular channel 140 a isconfigured to slidably receive surface feature 126 of hub 124 ofinstrument drive unit 100 therein. Lower annular channel 140 b isconfigured to slidably receive surface feature 128 of motor pack 122 ofinstrument drive unit 100 therein. Upper and lower annular channels 140a, 140 b each extend along at least a substantial circumference ofannular member 140.

Annular member 140 has a first pair of stops 142 a, 144 a formed inupper annular channel 140 a and a second pair of stops 142 b, 144 bformed in lower annular channel 140 b. In some embodiments, instead ofannular member 140 having a pair of stops disposed in each channel 140a, 140 b, annular member 140 may only have one stop disposed withinupper annular channel 140 a and one stop disposed within lower annularchannel 140 b. Stops 142 a, 144 a, 142 b, 144 b are generally squared,but may assume a variety of shapes, such as, for example, triangular,arcuate, polygonal, uniform, non-uniform, tapered, or the like. Stops142 a, 144 a, 142 b, 144 b and/or surface features 126, 128 may befabricated from lubricious (bushing) materials, such as, for example,PEEK, DELRIN, brass, UHMW, or the like.

The second pair of stops 142 b, 144 b of lower annular channel 140 b ofannular member 140 are circumferentially aligned (i.e.,co-circumferential) with surface feature 128 of motor pack 122 ofinstrument drive unit 100. As such, upon a threshold amount or degree ofrotation (e.g., about 180° to about 360° in a clockwise orcounter-clockwise direction) of motor pack 122, surface feature 128 ofmotor pack 122 abuts or engages one of the second pair of stops 142 b,144 b of lower annular channel 140 b of annular member 140. Inembodiments, the threshold amount of rotation may be about 1° to about360°. The first pair of stops 142 a, 144 a of upper annular channel 140a of annular member 140 are circumferentially aligned (i.e.,co-circumferential) with surface feature 126 of hub 124 of instrumentdrive unit 100. As such, upon a threshold amount or degree of rotation(e.g., about 180° to about 360° in a clockwise or counter-clockwisedirection) of annular member 140, one of the first pair of stops 142 a,144 a of annular member 140 abuts or engages surface feature 126 of hub124 of instrument drive unit 100 causing rotation of motor pack 122 tostop since hub 124 is rotationally fixed within U-shaped portion 110 aof outer shell 110. In embodiments, the threshold amount of rotation maybe about 1° to about 360°

The first pair of stops 142 a, 144 a of upper annular channel 140 a arecircumferentially spaced from one another to define a gap 146 atherebetween. The second pair of stops 142 b, 144 b of lower annularchannel 140 b are also circumferentially spaced from one another todefine a gap 146 b therebetween. Annular member 140 includes a firstsensor s140 a disposed within gap 146 a of upper annular channel 140 a,and a second sensor s140 b disposed within gap 146 b of lower annularmember 140 b. In some embodiments, sensors s140 a, s140 b may bepositioned at any suitable location on or within annular member 140 thatis adjacent respective stops 142 a, 144 a, 142 b, 144 b. Sensors s140 a,s140 b of annular member 140, sensor s126 of hub 124 of instrument driveunit 100, and sensor s122 of motor pack 122 of instrument drive unit 100are each in communication with one another and with control circuitry109 (FIG. 2 ) of surgical instrument holder 102 and are configured tosense the relative rotational or angular positions of one another. Eachof sensors s122, s126, s140 a, s140 b may be hall effect sensors, rotaryvariable differential transformers, variable reluctance sensors,potentiometers, capacitive rotary position sensors, optical encoders,and/or laser surface velocimeters.

In operation, the rotational position of surgical instrument 10 may bemonitored, and/or the rotation of surgical instrument 10 may be stopped,for example, to prevent potential damage to components of surgicalassembly 30 from over-rotation of surgical instrument 10. Motor “M” ofsurgical instrument holder 102 is actuated, which effects a rotation ofmotor pack 122 of inner shell 120 relative to hub 124 of inner shell120, in the manner described above. Throughout rotation of motor pack122, sensor s122 of motor pack 122 and sensor s140 b of lower annularchannel 140 b of annular member 140 sense each other's positionsrelative to one another and communicate the sensed relative position tocontrol circuitry 109 of surgical instrument holder 102. As such, therotational position of motor pack 122 and surgical instrument 10relative to hub 124 is known by control circuitry 109, which may ceaseactuation of motor “M” when motor pack 122 achieves a preset amount ofrotation that is stored in a memory (not shown). Additionally, controlcircuitry 109 may communicate the known relative rotational position ofmotor pack 122 from its starting position to display 6 (FIG. 1 ).

After motor pack 122 achieves a first threshold amount or degree ofrotation relative to hub 124 (e.g., about 180° to about 360°), surfacefeature 128 of motor pack 122 abuts one of the second pair of stops 142b, 144 b (depending on the direction of rotation of motor pack 122) oflower annular channel 140 b of annular member 140. In embodiments, thethreshold amount of rotation may be about 1° to about 360°. Upon theabutment of surface feature 128 of motor pack 122 with one of the secondpair of stops 142 b, 144 b of lower annular channel 140 b, continuedrotation of motor pack 122 causes annular member 140 to begin rotating.

During rotation of annular member 140 relative to hub 124, sensor s140 aof upper annular channel 140 a of annular member 140 and sensor s126 ofhub 124 sense each other's positions relative to one another andcommunicate the sensed relative position to control circuitry 109 ofsurgical instrument holder 102. As such, the rotational position ofmotor pack 122 and surgical instrument 10 relative to hub 124 is known.After annular member 140 achieves a second threshold amount or degree ofrotation relative to hub 124 (e.g., about 180° to about 360°), caused bythe continued rotation of motor pack 122, one of the first pair of stops142 a, 144 a of upper annular channel 140 a of annular member 140 abutssurface feature 126 of hub 124 of instrument drive unit 100 causingannular member 140, and motor pack 122 with surgical instrument 10, tostop rotating. In this way, a continued actuation of “M” of surgicalinstrument holder 102 will fail to result in a rotation of motor pack122, thereby preventing any damage from occurring to any components ofsurgical assembly 30 from the over-rotation of motor pack 122. Inembodiments, the threshold amount of rotation may be about 1° to about360°

A rotation of motor pack 122 in the opposite direction will repeat theprocess described above until motor pack 122 is prevented from rotatingby surface feature 126 of hub 124 of instrument drive unit 100 oranother surface feature (not shown) of hub 124 of instrument drive unit100. It is contemplated that prior to performing a surgical procedure,instrument drive unit 100 may be checked to determine that it is capableof achieving its full rotation in both rotational directions. Inparticular, motor pack 122 will be rotated in a first direction (e.g.,clockwise) until it is stopped, and motor pack 122 will then be rotatedin a second direction (e.g., counter-clockwise) until it is stopped. Amotor encoder (not shown), e.g., an incremental type, of instrumentdrive unit 100 may be checked during this process. After motor pack 122is rotated to its two stopping points, it is repositioned to be betweenthe two stopping points.

It is contemplated that the threshold amount or degree of rotation ofmotor pack 122 is set based on the position that stops 142 a, 144 a, 142b, 144 b are placed within their respective upper and lower annularchannels 140 a, 140 b. In some embodiments, the threshold amount ordegree of rotation may be more or less than 180° or 360° and may beabout 360° to about 720°. In embodiments, the threshold amount ofrotation may be about 2° to about 720°

It is contemplated, in accordance with an embodiment of the presentdisclosure, that control circuitry 109 may incorporate a highlytoleranced resistor “R” (not shown) with an extremely low resistance,about 0.05 ohms, that is added to a low side of an H-bridge responsiblefor driving motor “M” of surgical instrument holder 102. In operation,control circuitry 109 measures a voltage “V” drop across resistor “R.”By measuring the voltage “V” drop across resistor “R,” control circuitry109 may calculate an amount of current “I” flowing through resistor “R”using Ohm's Law:V=IR

In a DC electric motor, which motor “M” may be constructed as, current“I” is directly related to the amount of torque “τ” being developed byusing a relation, e.g., the Torque Constant (K_(m)). Accordingly,control circuitry 109 can calculate the amount of torque “τ” beingapplied to motor “M” according to the following equation:τ=(Km)(I)

Reference may be made to U.S. Pat. No. 8,517,241, filed on Mar. 3, 2011,for a detailed description of an exemplary embodiment of a controlcircuitry configured to calculate an amount of torque being applied tomotors, the entire contents of which are incorporated by referenceherein.

During a normal rotation of surgical instrument 10, a certain orpredetermined force profile is expected to be seen by control circuitry109, e.g., either a current v. time profile (not shown) or a current v.distance profile (not shown). In use, an actuation of motor “M” effectsa rotation of motor pack 122 of instrument drive unit 100 as describedabove. A rotation of motor pack 122 ultimately places surface feature128 of motor pack 122 into engagement with one of the second pair ofstops 142 b, 144 b of lower annular channel 140 b of annular member 140.Upon surface feature 128 of motor pack 122 engaging or coming intocontact with one of the second pair of stops 142 b, 144 b of annularmember 140, a static inertia of annular member 140 must be overcome by acertain threshold amount of added torque provided by motor “M.” Theadditional torque required to begin rotating annular member 140 changesa condition of motor “M,” which is a change in current “I” delivered tomotor “M,” which is a different amount of current compared to theexpected force profile stored in control circuitry 109.

This increase in current “I” or current spike is registered by controlcircuitry 109, and control circuitry 109 can reasonably assume thatsurgical instrument 10 has rotated the threshold amount from itsoriginal position. In particular, the current spike indicates that motorpack 122 has rotated a predetermined threshold (e.g., about 180°) fromits original rotational position. Since surgical instrument 10 rotateswith motor pack 122, the threshold amount of rotation of motor pack 122registered by control circuitry 109 correlates to the same thresholdamount of rotation traveled by surgical instrument 10 about itslongitudinal axis “X.” Display 6 (FIG. 1 ) may be provided to indicate,in the form of a number of degrees, the amount of rotation of surgicalinstrument 10.

Continued rotation of surgical instrument 10 eventually causes one ofthe first pair of stops 142 a, 144 a of upper annular channel 140 a ofannular member 140 to abut or engage surface feature 126 of hub 124,which results in another current spike and an instruction to ceasedelivering current to motor “M,” thereby ceasing rotation of motor pack122, and therefore rotation of surgical instrument 10. It is envisionedthat surface feature 126 of hub 124 may physically resist or preventfurther rotation of motor pack 122.

In some embodiments, instrument drive unit 100 may include a singleannular member or two or more annular members having any suitable numberof variously spaced surface features or tabs. It is further contemplatedthat the instrument drive unit 100 may include one or more hubs and anannular member corresponding to each hub.

With reference to FIGS. 7 and 8 , the instrument drive unit 100 (FIG. 3) may include a plurality of annular members 140, 240, 340 in a stackedconfiguration. Having more than one annular member allows for anincreased amount of rotation of the motor pack 122 relative to the hub124. In some embodiments, more than three annular members may beprovided. In embodiments, the motor pack 122 may rotate more than 720°.The second and third annular members 240, 340 are similar to the firstannular member 140 and will therefore only described with the level ofdetail deemed necessary.

The second annular member 240 defines a lower annular channel 242 andincludes a pair of stops 242 a, 242 b formed in the lower annularchannel 242. The stops 242 a, 242 b are circumferentially spaced fromone another to define a gap 246 therebetween. The second annular member240 includes a sensor s240 disposed within gap 246. Sensor s240 ofsecond annular member 240 is in communication with sensor s126 of hub124 of instrument drive unit 100 and sensor s122 of motor pack 122 ofinstrument drive unit 100. In embodiments, the sensor s240 of secondannular member 240 may be in communication with sensor s140 b (FIG. 6 )of lower annular channel 140 b of annular member 140.

The third annular member 340 is disposed between the first and secondannular members 140, 240. While not explicitly illustrated, the thirdannular member 340, like the first and second annular members 140, 240,may define upper and lower annular channels, and may include stops andsensors in each of its channels.

In operation, each of the annular members 140, 240, 340 is able to sensetheir rotational positions relative to one another due to the sensorsassociated with each. In addition, due to the interaction of the variousstops of the annular members 140, 240, 340, a threshold amount ofrotation of the motor pack 122 results in a rotation of the secondannular member 240, a threshold amount of rotation of the second annularmember 240 results in a rotation of the third annular member 340, and athreshold amount of rotation of the third annular member 340 results ina rotation of the first annular member 140.

As described above, after first annular member 140 achieves a thresholdamount or degree of rotation relative to hub 124 (e.g., about 180° toabout 360°), caused by the continued rotation of motor pack 122, one ofthe first pair of stops 142 a, 144 a of upper annular channel 140 a ofannular member 140 abuts surface feature 126 of hub 124 of instrumentdrive unit 100 causing annular member 140, and motor pack 122 withsurgical instrument 10, to stop rotating. In this way, a continuedactuation of motor “M” of surgical instrument holder 102 will fail toresult in a rotation of motor pack 122, thereby preventing any damagefrom occurring to any components of surgical assembly 30 from theover-rotation of motor pack 122.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications of variousembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended thereto.

The invention claimed is:
 1. An instrument drive unit, comprising: ahub; a motor pack coupled to the hub and configured to rotate relativeto the hub about a longitudinal axis defined by the motor pack; and atleast one annular member disposed between the hub and the motor pack,wherein the motor pack is configured rotate relative to the at least oneannular member from a first position to a second position upon which afurther rotation of the motor pack drives a rotation of the at least oneannular member relative to the hub.
 2. The instrument drive unitaccording to claim 1, wherein the at least one annular member isconfigured to rotate with the motor pack from a first position of the atleast one annular member to a second position of the at least oneannular member, in which the at least one annular member and the motorpack are prevented from rotating relative to the hub.
 3. The instrumentdrive unit according to claim 2, wherein the at least one annular memberhas a proximal surface feature and a distal surface feature, a proximalend portion of the motor pack has a surface feature configured to engagethe distal surface feature of the at least one annular member upon themotor pack moving to the second position, and the hub has a surfacefeature configured to engage with the proximal surface feature of the atleast one annular member when the at least one annular member is movedto the second position.
 4. The instrument drive unit according to claim3, wherein the at least one annular member defines: a proximal annularchannel, the proximal surface feature being formed in the proximalannular channel; and a distal annular channel, the distal surfacefeature being formed in the distal annular channel.
 5. The instrumentdrive unit according to claim 4, wherein the surface feature of themotor pack is a curved projection slidably received within the distalannular channel of the at least one annular member, and wherein thesurface feature of the hub is a curved projection slidably receivedwithin the proximal annular channel of the at least one annular member.6. The instrument drive unit according to claim 3, wherein the surfacefeature of the hub extends distally from the hub, and the surfacefeature of the motor pack extends proximally from the proximal endportion thereof.
 7. The instrument drive unit according to claim 3,wherein each of the motor pack, the at least one annular member, and thehub has a sensor in communication with one another and configured tosense the relative rotational positions of one another.
 8. Theinstrument drive unit according to claim 7, wherein the sensor of themotor pack is disposed adjacent the surface feature thereof, the sensorof the at least one annular member is disposed adjacent the proximal ordistal surface feature, and the sensor of the hub is disposed adjacentthe surface feature thereof.
 9. The instrument drive unit according toclaim 7, wherein at least one of the sensors of each of the motor pack,the at least one annular member, and the hub is at least one of a halleffect sensor, a rotary variable differential transformer, a variablereluctance sensor, a potentiometer, a capacitive rotary position sensor,an optical encoder, or a laser surface velocimeter.
 10. The instrumentdrive unit according to claim 1, wherein the at least one annular memberis a hollow ring having an H-shaped transverse cross-sectional profile.11. The instrument drive unit according to claim 1, further comprisingan outer shell, wherein the hub is non-rotatably received within theouter shell, the motor pack having a proximal end portion rotatablycoupled to the hub.
 12. The instrument drive unit according to claim 11,wherein the motor pack has a distal end portion configured to benon-rotatably coupled to a proximal end portion of an electromechanicalinstrument.
 13. The instrument drive unit according to claim 12, whereinthe motor pack of the instrument drive unit is configured to actuatefunctions of the electromechanical instrument, and wherein theelectromechanical instrument rotates with rotation of the motor pack.14. An instrument drive unit for use with a robotic arm, the instrumentdrive unit comprising: an outer shell configured to be coupled to arobotic arm; a drive motor selectively moveable in an orbit within theouter shell around a central axis; an interface coupled to the outershell and configured to be selectively couplable to a surgicalinstrument; and a drive motor output coupled to the drive motor andconfigured to be coupled to an input of a surgical instrument when theinterface is coupled to an interface of the surgical instrument.
 15. Theinstrument drive unit according to claim 14, wherein the drive motor isencased within the outer shell.
 16. The instrument drive unit accordingto claim 14, wherein the outer shell remains stationary when the drivemotor is selectively moved in the orbit.
 17. The instrument drive unitaccording to claim 16, wherein the drive motor is a plurality of drivemotors selectively movable as a group in the orbit within the outershell, each of the plurality of drive motors having a drive motor outputconfigured to be coupled to a respective input of the surgicalinstrument.
 18. The instrument drive unit according to claim 17, whereinthe instrument drive unit is configured to rotate the surgicalinstrument about the central axis when the interface of the instrumentdrive unit is selectively coupled to an interface of the surgicalinstrument.
 19. The instrument drive unit according to claim 18, furthercomprising an electro-mechanical actuator coupled to at least one of thedrive motors, the electro-mechanical actuator configured to rotate thesurgical instrument about the central axis while moving the drivemotors, the drive motor outputs, and the respective inputs of thesurgical instrument in the orbit within the outer shell when theinterface of the surgical instrument is selectively coupled to theinterface of the instrument drive unit.
 20. An instrument drive unit foruse with a robotic arm, the instrument drive unit comprising: an outershell configured to be selectively coupled to a robotic arm; and aninner shell removably received within the outer shell and including: ahub non-rotatably received within the outer shell and having a distallyextending surface feature; a motor pack including a proximal endrotatably coupled to the hub, and a surface feature extending proximallyfrom the proximal end thereof; a first annular member defining an upperannular channel having the surface feature of the hub received therein,the first annular member having a stop formed in the upper channelthereof; a second annular member associated with the first annularmember and defining a lower annular channel, the second annular memberhaving a stop formed in the lower annular channel thereof, wherein uponthe motor pack achieving a threshold amount of rotation relative to thehub, the surface feature of the motor pack abuts the stop of the lowerannular channel of the second annular member to rotate the secondannular member relative to the hub, and wherein upon the first annularmember achieving a threshold amount of rotation relative to the hub, thestop of the upper annular channel of the first annular member abuts thesurface feature of the hub stopping further rotation of the motor pack.